Book digitized by Google and uploaded to the Internet Archive by user tpb.
Title from cover
In 1926 the society decided to discontinue the regular publication of its Proceedings and to enlarge its journal. The Proceedings continued, therefore, only for material unsuited to the journal, the volumes appearing at irregular intervals
Vols. 20-21 form a combined volume issued in two parts with continuous paging, published 1928, and 1933 respectively